Means for preventing explosions of steam-boilers



1). T. LAWSON. Means for Preventing-Explosions of Steam-Boilers.

'- No., 227-,024. Patented April 27,1880.

T I 1 1 CD Z I I Ii WITNESSES: INVENTOR:

-W#* 5 ATTORNEYS.

N. PETERS, PHQTO-UTHOGRAPHER. WASHINGTON. D. C.

UNITED STATES PATENT OFFICE.

' DANIEL T. LAWSON, OF WELLSVILLE, OHIO.

MEANS FOR PREVENTING EXPLOSIONS OF STEAM-BOILERS.

SPECIFICATION forming part of Letters Patent No. 227,024, dated April27, 1880.

Application filed November 4, 1879.

To all whom it may concern Be it known that I, DANIEL T. LAwsoN, ofWellsville, in the county of Columbiana and State of Ohio, have inventeda new and Improved Means for Preventing Explosions of Steam-Boilers; andI do hereby declare that the following is a full, clear, and exactdescription of the same, reference being had to the accompanyingdrawings, forming part of this specification, in which- Figure 1 is avertical longitudinal section. Fig. 2 is a transverse section.

Water boils under the normal pressure of the atmosphere at 212Fahrenheit. Under a pressure of ten pounds to the square inch a heat of239 is required to make it boil under fifty pounds to the square inch,298 is required, and under one hundred pounds pressure to the squareinch, 338 of heat is required in all the water in the boiler to keep thesteampressure to that pointi. e., to one hundred pounds to the squareinch-and just as the steam-pressure is increased so the heat in thewater must be proportionately increased, or else the steam-pressurerequired cannot be had.

When water is thus superheated it becomes as explosive as gunpowder; butit does not explode in the same manner, as powder explodes by chemicalunion upon ignition, while superheated water explodes by bursting intosteam from a reduction of pressure. Thus the engineer opens thethrottle-valve and the cylinder is instantly filled with steam, whichcreates a vacuum to that extent in the boiler. The superheatedwater thenimmediately jumps to fill the vacuum, and is met by the valve, instantly cutting off the escape into the cylinder, which causes aconcussion on every square inch in the boiler much greater than theregular pressure of the steam. I have abundant reason to believe that itis this concussive action which causes the numerous and mysteriousboiler-explosions, and which cause is wholly independent of the amountof waterin the boiler-in fact, the greater the amount of It thus acts tocondense the steam, and for an instant suddenly reduces the pressure.Immediately after the momentary condensation the superheated water againbursts into steam, and by a concussive action involves a strain of thesame general character as that which is constantly going on during theescape of steam through the cylinder-ports, but of a more intensecharacter.

Myinvention, which isbased upon this theory, consists in reducing theconcussive strain produced by the impulsive and intermittent escape ofsteam to the cylinders to an approximately uniform pressure by renderingthe evolution or passage of steam from the water to the steam spaceapproximately constant and independent of the intermittent dischargesfrom the steam-space to the cylinder; and themeans for accomplishing thesame consist in a boiler constructed with a partition interveningbetween the water-space and the space whence the steam is taken tosupply the cylinder, and feeding the steam as it is generated through avalve or orifice in said partition of a smaller size than the port oropening through which the steam passes into the cylinder. By this meansthe normal'steampressure or steam-supply, when thus intermittently oralternately reduced, is restored gradually by reducing the flow from thewaterspace to the steam-space, so that the transformation of water intosteam is made approximately uniform in spite of the intermittent escapeof steam through the cylinders, and the boiler is thus relieved of theconstant wear and strain of the concussion.

In the drawings I show one example of my invention, in which Arepresents .a steamboiler, which may be of any approved shape and beprovided with fire-fines A A. a partition in the same, separating theboiler into two compartments, one of which, 0, con

result of my invention, should be smaller than the orifice through whichsteam is fed to the cylinder. For practical purposes it should be aboutone-fourth as large as said outlet, and when so relatively proportionedit will be found that although a considerable body of steam may besuddenly takenout of the steamspace proper by the opening of thecylindervalve the protracted flow from the lower compartment to theupper compartment, caused by the smaller size of the orifice, retardsthe transformation of superheated water into steam through a period oftime sufliciently long, as compared with the strokes of the piston, tomake the liberation of steam practically uniform. In other words, thesuperheated water cannot jump in a body to supply the place of thedischarged steam and meet with a check by the sudden closing of theinduction-port, which produces a concussive strain on the boiler; butthe reduction of the size of the orifice through which the steamliberated from the water passes is such as to prolong the passage ofsteam through said orifice over the period when the induction-port valveis closed.

To avoid the concussion produced by condensation, I propose to introducethe water at a point so low that no cold water can ever come in directcontact with the steam, and with a downward instead of an upwardinjection. If, perchance, any cold water should thus come in contactwith the steam, my invention of the partition and opening therethroughstill acts beneficially, for the reason that the steam-space over thewater in the lower compartment is limited in my invention and thecondensation of the steam in this space is limited in its effect.

In fitting up old boilers with my improvement I may build a supplementalsteam-space above the old boiler and connect their cham-' bers by anorifice of the relative size described, or I may interpose the partitionbetween the boiler and the steam-dome.

Having thus described my invention, what I claim as new is-- 1. Themethod of preventing concussive strains in boilers due to theintermittent escape of steam into the cylinder, which consists inretarding or prolonging the flow of the steam from the water to thesteam space through a greater length of time than is allowed for theescape of the same quantity of steam from the steam-space, as described.

2. A steam-boiler adapted to carry a permanent bulk of water, having apartition dividin g themain steam-space from the water-space, with anopening in said partition of less area than the opening through whichthe steam is led from the steam-space to the cylinder.

The above specification of my invention signed by me this 30th day ofOctober, 1879.

D. 'l. LAWSON.

Witnesses Enwn. W. BYRN, CHAS. A. PETTIT.

